1. Field of the Invention
The invention relates to an apparatus which can continuously manufacture a semiconductor device of a large area, particularly, a laminated semiconductor thin film device such as a photoelectromotive device or the like onto a substrate and also relates to a manufacturing method using such an apparatus.
2. Related Background Art
Hitherto, as a method of continuously manufacturing a semiconductor device such as a photoelectromotive device or the like onto a substrate, there has been proposed a method whereby an independent film forming chamber to form layers of the semiconductor device is provided and each of the semiconductor layers is formed in the film forming chamber.
For instance, a continuous plasma CVD method using the Roll to Roll system is disclosed in the specification of U.S. Pat. No. 4,400,409. According to such a method, a plurality of glow discharge regions are provided, a sufficiently long belt-shaped substrate of a desired width is arranged along a path in which the substrate sequentially penetrates the glow discharge regions, the substrate is continuously conveyed in the longitudinal direction while depositing semiconductor regions of the conductivity type which are needed in the glow discharge regions, so that a device having a semiconductor junction can be continuously manufactured.
In the specification, a gas gate is used to prevent a film forming gas, which is used upon formation of each semiconductor layer, namely, a dopant gas, from being diffused and mixed into the other glow discharge regions.
Practically speaking, a means is used such that the glow discharge regions are separated by slit-shaped separating passages, a flow of a gas for scavenging such as Ar, H.sub.2, or the like is further formed on the separating passages or exhaust means is provided on the separating passages, and the gases flowing into from the adjacent film forming chambers are exhausted.
Further, in the specification of U.S. Pat. No. 4,462,332, a method is disclosed whereby a belt-shaped substrate of a magnetic material comes into pressure contact with one of the wall surfaces of the gas gate by a magnetic force and the belt-shaped substrate is conveyed in side contact with the wall surface. According to such a method, since the substrate position in the gas gate is stable, an interval between the substrate surface and the wall surface of the gas gate can be sufficiently narrowed and since the back surface of the substrate is adhered to the gas gate wall, an excellent separating performance of the gas between the adjacent discharge regions is obtained.
FIG. 8 is a diagram of the gas gate shown in the above patent specification. FIG. 9 shows a diagram of a gas gate in which the substrate does not come into contact with the wall surface of the gas gate. In the diagrams, reference numerals 801 and 901 denote slit-shaped separating passages; 803 and 903 gas gate walls; 804 and 904 belt-shaped substrates; 805 and 905 gas introducing pipes for scavenging; and 806 a magnet.
According to the above method, however, since the belt-shaped substrate is conveyed in slide contact with the wall surface of the gas gate, a frictional force at the gas gate easily increases as compared with the method whereby the substrate is conveyed while keeping a gap between the substrate and the gas gate wall surface. When the frictional force increases, scratches are formed on the back surface of the belt-shaped substrate and a pressure is applied from the substrate side to the deposited film. On the other hand, a tension upon conveyance of the belt-shaped substrate increases and a pressure is applied from the front surface side of the substrate to the deposited film when the belt-shaped substrate after completion of the film deposition is wound up, so that a number of defects of the semiconductor device are generated.
In the case where a thin material or a material which can be easily extended is used as a belt-shaped substrate, when the frictional force at the gas gate increases, the substrate is extended or wrinkles occur due to an increase in tension upon conveyance of the belt-shaped substrate. Consequently, a peel-off, cracks, or the like of the deposited film occur and defects easily occur in the semiconductor device.
Therefore, as shown in the specification of U.S. Pat. No. 4,462,332, a material of a low frictional force is used in a contact portion of the gas gate, or as shown in the specification of U.S. Pat. No. 4,438,724, a long groove is provided in the contact portion of the gas gate in the progressing direction of the belt-shaped substrate and a contact area between the belt-shaped substrate and the gas gate wall surface is reduced or the like, thereby decreasing the frictional force.
According to the above conventional methods, since it is impossible to sufficiently reduce the frictional force while keeping the adhering state between the belt-shaped substrate and the gas gate wall surface, a strong pressure is certainly applied to the deposited film and defects frequently occur in the semiconductor device. To convey the belt-shaped substrate, a strong tension is surely needed, so that a peel-off or cracks of the deposited film easily occur. A thin material or a material which can be easily extended cannot be used as a substrate material. There is a limitation in the material which is used as a substrate.
Particularly, in the case of a tandem type solar battery or the like having a large number of layers to be deposited, the number of gas gates which the belt-shaped substrate penetrates in the manufacturing steps of a semiconductor device is large and the frictional force also increases in accordance with an increase in number of gas gates, so that there are large influences such as deterioration of productivity due to the occurrence of defects, limitation of the substrate material, and the like.